Gear train arrangements

ABSTRACT

Gear train arrangements for transmitting a power from a driving source to a driven member at more than three speeds in one direction and another speed in the opposite direction, the gear train arrangements using basically three planetary gear sets and at least five friction elements such as clutches and brakes which are selectively actuated to selectively engage the rotary members of the three planetary gear sets to deliver an output power at the above said speeds. The gear train arrangements are specifically adapted for use in an automatic transmission system of a motor vehicle using a torque converter or fluid coupling.

United States Patent [191 Mori et a1.

[ GEAR TRAIN ARRANGEMENTS [75] Inventors: Yoichi Mori, Yokohama; NobuoOkazaki, Chigasaki; Kunio Ohtsuka; Tetsuya lijima, both of Tokyo, all ofJapan [73] Assignee: Nissan Motor Company, Limited,

Yokohama City, Japan [22] Filed: Sept. 13, 1972 [21] Appl. No.: 288,495

Related U.S. Application Data [62] Division of Ser. No. 30,496, April21, 1970.

[30] Foreign Application Priority Data June 4, 1969 Japan 44-43275 [52]U.S. Cl. 74/759 [51] Int. Cl. F16h 57/10 [58] Field of Search 74/759 [56] References Cited UNITED STATES PATENTS 2,813,437 11/1957 Kelbel et al74/759 [11] 3,811,343 [451 May 21, 1974 3,523,468 8/1970 Kepner 74/759Primary Examiner--Arthur T. McKeon Attorney, Agent, or Firm'DePaoli &OBrien 5 7] ABSTRACT Gear train arrangements for transmitting a powerfrom a driving source to a driven member at more than three speeds inone direction and another speed in the opposite direction, the geartrain arrangements using basically three planetary gear sets and atleast five friction elements such as clutches and brakes which areselectively actuated to selectively engage the rotary members of thethree planetary gear sets to deliver an output power at the above saidspeeds. The gear train arrangements are specifically adapted for use inan automatic transmission system of a motor ve hicle using a torqueconverter or fluid coupling.

2 Claims, 37 Drawing Figures PATENTEBIMI m4 SHEET 03 0F 15 #79 30 OUTPUTK PATENTEDIAYZI m4 3 8 1 1.343

sum as or 15 INPUTfiF) OUTPUT INPUT(R) PATENTEDlAm I974 SHEET, 10 0F 15INPUT OUTPUT F/g. /Ob

PATENTEDIAYZ] 1914 saw 12m 1s F/g. /2a

|NPUT(F) OUTPUT INPUT (R) PATENTEDIAY 21 19M 381 1.343 sum is or 15 Fig./30

OUTPUT RI Cl v SI 525* C2 R2 I S3 C3R3 PATENTEDIAYZI m4 3 811 3 sum 1 0F15 Fig. /4

PATiNtmmal m4 sum '15 0F 15 P3?! S3 I Fig. /7

GEAR TRAIN ARRANGEMENTS This is a division, of application Ser. No.30,496 now US. Pat. No. 3,701,293 filed Apr. 2|, 1970.

This invention relates to gear train arrangements for a transmissionsystem of a motor vehicle and, more particularly, to gear trainarrangements of planetary gear type adapted to provide basically fourforward and one reverse vehicle speeds.

A usual gear train arrangement using a planetary gear system is made upof a combination of one or more, similar or different, planetary gearsets each having one or more planet pinions and is operated throughactuation of friction elements such as clutches and brakes which arearranged to attain a desired combination of gear ratios. Typical of suchgear train arrangement is the one that uses three simple planetary gearsets which are combined together to provide three forward and onereverse vehicle speeds. (It may be noted that the term simple planetarygear as herein used'is intended to refer to a planetary gear set havinga single planet pinion.)

Foremost of the practical requirements of a gear train arrangement toattain an increased number of vehicle speeds is a wide selection of thecombinations of gear ratios, which requirement, however, is reflected byan increased number of component parts of the gear train arrangement andcomplicated gear shifting operations.

In order that the gear train be snugly accommodated within a limitedspace in the transmission system, every component of the planetary gearsystem should be as small in dimensions as possible. From the view pointof production economy, moreover, it is desired that the number of thecomponent parts of the gear train be reduced to a minimum and that theparts corresponding in function be fabricated to be common in geometryto one another so as to permit of quantity production. Another importantrequirement of the gear train of a transmission system is the ease ofgear shifting operations.

It is, therefore, an object of the invention to provide gear trainarrangements adapted to provide basically four forward and one reversevehicle speeds.

Another object is to provide gear train arrangements providingessentially four forward and one reverse vehicle speeds with wideselection of the combinations of gear ratios.

Still another object is to provide gear train arrangements providingfour, or even more, forward and one reverse vehicle speeds, whicharrangements are constructed with a practically minimum number ofcomponent parts and nevertheless can provide practically any desiredcombination of gear ratios.

Still another object is to provide gear train arrangements that aresuited for quantity production.

Still another object is to provide gear train arrangements providingfour, or even more, forward and one reverse vehicle speeds with utmostease of gear shifting operations.

In order to achieve these and other objects, the invention proposes touse various combinations of basically three substantially identicallysized planetary gear sets which are operated by means of two or threeclutches and two or three brakes. The gear train arrangements using suchcombinations can be readily modified with incorporation of additionalminor arrangements into those providing five or six forward and onereverse vehicle speeds.

In the drawings:

FIGS. 1 to 8 are sectional views schematically showing various preferredembodiments of the invention, each of which embodiments uses threeplanetary gear sets with two clutches and three brakes to provide fourforward and one reverse vehicle speeds;

FIG. 9 is similar to FIGS. 1 to 8 but shows other embodiments usingthree planetary gear sets with three clutches and two brakes to providefour forward and one reverse vehicle speeds;

FIGS. 10, 11, and 12 are views illustrating still other embodimentsusing three planetary gear sets with three clutches and three brakes toprovide four forward and one reverse vehicle speeds;

FIG. 13 is a view illustrating still another embodiment using four(including one auxiliary) planetary gear sets with three clutches andfour brakes to provide four forward and one reverse vehicle speeds;

FIG. 14 is a view illustrating still another embodiment using threeplanetary gear sets with three clutches and three brakes to provide fiveforward and one reverse vehicle speeds;

FIG. 15 is a view illustrating still another embodiment using four(including one auxiliary) planetary gear sets with two clutches andthree brakes to provide five forward and one reverse vehicle speeds;

FIG. 16 is a view illustrating still another embodiment using four(including one auxiliary) planetary gear sets with three clutches andfour brakes to provide six forward and one reverse vehicle speeds;

FIGS. la to 16a are diagrams each showing the different revolutionspeeds of the individual rotary members of the planetary gear sets usedinthe embodiment illustrated in the corresponding figure out of FIGS. 1to 16; and

FIGS. lb, 4b, 6b, 7b, 8b, 9b and 10b are views each showing amodification of the embodiment illustrated in the corresponding figurewithout the subscript.

Corresponding reference numerals and characters represent like membersin all the figures.

It may be noted in regard to the drawings that only the upper half ofeach gear train arrangement is herein shown for simplicity ofillustration because the gear train arrangement is generally symmetricalwith respect to the input and output shafts.

First referring to FIG. 1, the gear train according to one embodiment ofthe invention is, as customary, con nected to one end with an enginethrough an input shaft 10 and a torque converter or fluid coupling (notshown) and at the other end with a differential (not shown) through aninput shaft 11 of the transmission system.

The gear train as shown includes a first, second and third planetarygear sets l2, l3 and 14, all of which are constructed as simpleplanetary gear sets which are fabricated to be substantially identicalin geometry with each other.

The first planetary gear set 12 comprises an outer ring gear R,, aplanet pinion P, meshing with the outer ring gear, and a sun gear S,meshing with the planet pinion. The second planetary gear set 13similarly comprises an outer ring gear R a planet pinion P meshing withthe ring gear, and a sun gear S meshing with the planet pinion. Thethird planetary gear set 14 also similarly comprises an outer ring gearR a planet pinion P meshing with the ring gear, and a sun gear 5;,meshing with the planet pinion. The planet pinions P,, P, and P arecarried on and revolved by pinion carriers 15, I6 and 17, respectively.The ring gears, pinion carriers and sun gears are all roatable about acommon axis which is in line with the axes of the pinion carriers. Moredetailed discussion of the constructions and motions of the planetarygear set per se is herein omitted because they are well known in theart.

The ring gear R, of the first planetary gear set 12 is constantlyconnected to and rotatable with the planet pinion P of the secondplanetary gear set 13 through the pinion carrier which forms part of adrum 18. The sun gears S, and S of the first and second planetary gearsets 12 and l3, respectively, are constantly connected to and rotatablewith the input shaft of the transmission through mechanical linkages l9and 20, respectively. The ring gear R is constantly connected to androtatable with the sun gear S of the third planetary gear set 14 througha drum 21. The pinion carrier 17 is constantly connected to androtatable with the output shaft 11 of the transmission to carry anoutput power to the differential (not shown).

The pinion carrier of the planet pinion P, is connected to a'first bandbrake B, which, when applied, holds the planet pinion P, stationary. Thedrum 18 interconnecting the ring gear R, and planet pinion P coacts witha second band brake B which, when applied, holds both the ring gear R,and planet pinion P stationary. The drum 21 interconnecting the ringgear R and sun gear 8;, coacts with a third band brake B which, whenapplied, holds both the ring gear R and sun gear 8;, stationary.

Two clutches C, and C are provided to selectively connect the ring gearR to the drum 21 and the input shaft 10, respectively.

Now, it is well known in the art that, assuming the revolution speeds ofa ring gear, sun gear and pinion carrier of a given planetary gear setare Nr, Ns and Np, respectively, and the ratio of the number of teeth ofthe sun gear to the number of teeth of the ring gear is a, then thefollowing equation holds:

Thus, for planetary gear sets l2, l3 and 14, the following equations canbe derived:

(01 l)-Np Nr, or -Ns,, and

(a3 NI}, a 'NS where the subscripts 1, 2 and 3 represent the first,second and third planetary gear sets 12, 13 and 14, respectively.

In consideration of the constant connections between some of the rotarymembers of the planetary gear sets, the following equations .hold:

Ns, Ns,, Nr, Np and Nr Ns,. The speeds Ns, and Np, are equal to therevolution speeds of the input and output shafts l0 and 11,respectively.

These mathematical relations between the revolution speeds of theindividual rotary members of the planetary gear sets can be graphicallyillustrated in FIG. 1a, wherein points L, M and N are given on a lineOo' in such a manner that the following relations are maintained:

Thus, the points 0, L, M, N and 0' stand for the relations between thoseindividual rotary members of the planetary gear sets which arerespectively shown below these points. The speed vector of each rotarymember of the planetary gear sets is indicated by a length from therespective point 0, L, M, N and O on a line extending therefrom.

When, in operation, the first speed is to be selected, the second clutchC is coupled and the first brake B, applied. The ring gear R of thethird planetary gear set 14 now rotates with the input shaft 10 and theplanet carrier 15 is held stationary, so that the following equationshold:

In this condition, the sun gear S, is rotated directly by the inputshaft 10 with the plane pinion P, held stationary so that the ring gearR, and the pinion carrier 16 of the planet pinion P rotate at a speedcorresponding to a vector NN, in FIG. la. With the sun gear 8, rotatingwith the input shaft 10, the ring gear R and the sun gear S rotate at aspeed corresponding to a vector 00,. The ring gear R rotating with theinput shaft and the sun gean S rotating at a speed corresponding to 0'0,the pinion carrier 17 of the planet pinion P rotates at speedcorresponding to AA, providing a gear ratio for the first forwardvehicle speed.

The gear ratio establishing the first speed thus delivered from theoutput shaft 11 is thus expressed as:

When the vehicle speed is to be shifted from the first to the secondspeed, then the first brake B, is released and instead the second brakeB is applied with the second clutch C kept coupled. Thus:

Nr, N12 0.

With the brake B applied, the planet pinion P is held stationary and thesun gear 8, rotates with the input shaft 10 so that the ring gear R andthe sun gear 8;, are rotated at a speed corresponding to a vector 0'0 inFIG. 1a. With the clutch C coupled, the ring gear 8,, rotates with theinput shaft 10 so that the pinion carrier 17 of the planet pinion Protates at a speed corresponding to a vector AA providing a gear ratiofor the second forward speed.

The gear ratio for the second vehicle speed is thus expressed as:

Ns,/Np l 01 11 0: 1:2

When the speed is to be shifted from the second to the third speed, thesecond brake B is released and instead the third brake 3;, applied withthe second clutch C kept coupled. Thus:

Nr2 NS3 O and Nrg N82.

With the brake 8,, applied and the clutch C coupled, the sun gear 8,, isheld stationary and the ring gear R rotates with the input shaft 10 sothat the pinion carrier 17 of the planet pinion P rotates at a speedcorresponding to a vector AA which provides a gear ratio to establishthe third forward speed.

The gear ratio for the third speed is thus expressed as:

Ns,/N6 l 01 When the speed is to be shifted from the third to the fourthspeed, then the third brake B is released and the first clutch C,coupled with the second clutch C kept coupled. Thus:

Nrg Nrg N82.

With the brakes B,, B and B, released and the clutches C, and C coupled,all the planetary gear sets rotate with the input shaft so that therevolution speed of the pinion carrier 17 of the planet pinion P isequal to the speed of the input shaft, as indicated by a vector AA, inFIG. la.

The gear ratio for the fourth speed attained in this manner is thusexpressed as:

When the vehicle is to be moved backwardly, the first clutch C, iscoupled and the second brake B applied. Thus:

Nr Nr and Nr, Np 0.

With the brake B applied and the sun gear S rotating with the inputshaft 10, the ring gear R and the sun gear S rotate at a speedcorresponding to a vector 0'0 Since, in this instance, the clutch C, iscoupled, the ring gear R also rotates at a speed equal to the speed ofthe ring gear R and sun gear S Both the ring gear R and sun gear Srotating at the speed corresponding to 0'0 the planetary gear set 14rotates in its entirety at this speed. The output shaft 11 is thusrotated at a speed corresponding to 0'0, in a direction opposite to therotation of the input shaft 10.

The gear ratio for the reverse speed thus established is thus expressedas:

The conditions of the clutches and brakes for the different vehiclespeedsand the gear ratios attained under these conditions are tabulatedin Table 1, wherein the sign refers to that the related clutch or brakeis actuated and the sign refers to that the clutch or brake is keptreleased. The gear ratios indicated in the parentheses are derived onthe assumption that a, a 01,, 0.45. (This will apply to all the tableswhich are hereinafter presented.)

In order to streamline the shifting between the first and second speeds,a one-way clutch 23 may be provided on the planet carrier of the firstplanetary gear set 12, as illustrated in FIG. lb, if desired.

provide four forward and one reverse speeds with use of three identicalplanetary gear sets l2, l3 and 14 which are operated by two clutches C,and C and three b nd b a sss r, B2 ndBa- The first clutch C, is linkedon the one hand with the input shaft 10 of the transmission and on theother with the ring gear R, of the first planetary gear set 12. Thesecond clutch C which is also linked with the input shaft 10, is linkedwith both the sun gears S, and S of the first and second planetary gearsets 12 and 13, respectively, through a drum 24 for the first band brakeB,. The sun gears S, and S are as a result constantly connected togetherand rotatable with each other. The planet pinion P, of the firstplanetary gear set 12 constantly connected to and rotatable with thering gear R of the second planetarys gear set 13, sun gear 8,, of thethird planetary gear set 14, and output shaft 11 of the transmissionthrough the pinion carrier 15 and an inter mediate shaft 25. The planetpinion P of the second planetary gear set 13 is constantly connected toand rotatable with the planet pinion P of the third planetary gear set14 through the pinion carriers 16 and 17 which form part of a drum 26for the second band brake B The ring gear R of the third planetary gearset 14 is connected IQ a dam 'IfQUht t i ba h a 3- The conditions of theclutches and the brakes for the different vehicle speeds and the gearratios attained in these conditions are tabulated in Table II; the gearratios are calculated in a manner similar to that discussed inconnection with the gear train of FIG. 1.

TABLE I C, C B, B 8;, Gear ratios Forward:

S .1 2 a i aud-0(2) (2 88) 2nd Haas (1.82)

l-a -a 1 Rev (2.22)

TABLE ll C1 C2 B1 B2 8;, Gear ratios Forward:

1st 1+m+ 2.4s)

2nd 1+ 5 1g we. a (1+ 3rd 1+a, (1.45) am 1 1.00)

Rev

When the first forward speed is selected, the clutch C, is coupled andthe brake B applied. In this instance, the operations of the individualrotary members will be easily understood if it is assumed that theoutput shaft 11 is first rotated to impart a rotational effort to theinput shaft conversely to the actual operation. Thus, if the outputshaft 1 1 is rotated at a speed corresponding to a vector AA, in FIG.2a, then the ring gear R and the pinion carrier of the planet pinion P,will rotate at the same speed as the output shaft 11. With the brake Bapplied, the planet pinion P is held stationary so that the sun gears Sand S, rotate at a speed corresponding to a 'vector OO,. Such rotationof the sun gear S, and the revolution of the planet pinion P, (whichrevolves at a speed equal to the revolution speed of the output shaft11) will dictate the speed at which the ring gear R of the firstplanetary gear set 12 rotates as represented by a vector 00 in FIG. 2a.The driving force is actually carried to the input shaft 10, not to theoutput shaft 11, so that the flow of rotation is exactly inverse fromthat discussed above. Thus, it is apparent that the first speedcorresponds with the vector AA, in FIG. 2a.

When the speed is shifted from the first to the second speed, then thebrake B is released and the brake B is applied with the clutch C, keptcoupled. Here, it is also assumed that the driving force is initiallytransferred to the output shaft 11. If the output shaft 11 is rotated ata speed corresponding to a vector AA, in FIG. it assuage-am, rotateswith the otitput shaft 11. The ring gear R being held stationary withthe brake 8;, applied, the pinion carriers 17 and 16 rotate at a speedcorresponding to a vector MM. Since, in this instance, the ring gear Rrotates with the output shaft 11 at a speed corresponding to the vectorAA the sun gears S and S, rotate at a speed corresponding to the vectorO'O,. The planet pinion P, is rotated with the pinion carrier 15rotating with the output shaft 11 that the second speed corresponds tothe vector AA in FIG. 2a.

When the speed is shifted from the second to the third speed, the brakeB, in lieu of the brake B is now applied with the clutch C, keptcoupled, so that the sun gears S, and S are held stationary and the ringgear R, rotates with the input shaft 10. The pinion carrier 15supporting the planet pinion P,, therefore, rotates at a speedscorresponding to a vector AA providing a gear ratio for the thirdforward speed.

When the speed is further shifted up fromthe third to the fourth speeds,all the brakes are applied and the clutches are coupled so that thefirst planetary gear set 12rotates in its entirety at the same speed asthe input shaft 10. The speed of the input shaft 10 is in this mannertransferred to the output shaft 11 as it is.

. For effecting the reverse movement of the vehicle, the clutch C iscoupled and the brake B applied. The sun gear S, now rotates with theinput shaft 10 with the planet pinion P held stationary so that the ringgear R rotates at a speed corresponding to a vector LL, which provides agear ratio to establish the reverse speed.

It will now be appreciated that the gear train of FIG. 2 is, similarlyto that of FIG. 1, adapted to provide ease of gear shifting operationsbecause the gear ratios can be changed merely by releasing only one ofthe clutches and brakes and actuating another one of them and that,since the output power can be derived from the intermediate section ofthe gear train without sacrificing the output torque, the gear train canbe utilized in a front-engine, front-driven or rear-engine, reardrivenmotor vehicle.

FIG. 3 illustrates still another form of the gear train according to theinvention constructed to provide four forward and one reverse speeds.The gear train also has three identical planetary gear sets 12, 13 and14 with two clutches C, and C, and three brakes B,, B 13 as shown.

The first clutch C, is linked on one side with the input shaft 10 and onthe other with the ring gear R, of the first planetary gear set 12through a drum 28 of the first band brake B,. The second clutch C islinked on one side with the input shaft 10 and on the other with the sungears 8,, S and S of the first, second and third planetary gear sets 12,13 and 14, respectively, through an intermediate shaft 29. The sun gears8,, S and S, are

. gear set 13 through a drum 30 for the second band brake B The pinioncarrier 16 of the planet pinion P of the second planetary gear set 13 isconstantly connected to and rotatable with the ring gear R of the thirdplanetary gear set 14 and is linked with the third brake B, through adrum 31. The pinion carrier 17 of the planet pinion P,, of the thirdplanetary gear set 14 is connected to the output shaft 11. A one-waybrake 32 is provided to prevent the planet pinion P and sun gear 8,,from rotating in a direction opposite to the rotation of the input shaft10. I

In consideration of the constant connections between some of the rotarymembers of the planetary gear sets in this embodiment, the followingrelations hold:

N11 Nr Np, Nr and Ns, Ns N83.

The conditions of the clutches and brakes for the different vehiclespeeds and the gear ratios attained in these conditions are tabulated inTable III.

N owIfoi the first forward speed, the clutch C is coupled with thebrakes B,, B and 8,, all released. The three planetary gear sets rotatetogether at the same speed as the input shaft 10. In this instance, thering gear R tends to rotate in a direction opposite to the direction ofrotation of the planetary gear sets because of the running resistance ofthe vehicle as transferred thereto from the wheel axles. Such tendencyis, however, obstructed by the one-way brake 32 so that the relation Nr,0 holds. The ouptut speed thus delivered to the output shaft 11 isindicated as a vector LL, in FIG. 3a.

When the speed is shifted to the second speed, the brake B is appliedwith the clutch C coupled. The sun gear 8,, being rotated by the inputshaft 10 through the clutch C and intermediate shaft 29, the pinioncarrier 16 of the planet pinion P rotates at a speed corresponding to avector MM, in FIG. 3a with the ring gear R held stationary by the brakeB The ring gear R thus rotates at the same speed as the pinion carrier16, while the sun gear S is rotated at the same speed as the input shaft10. The result is that the pinion carrier 17

1. A gear train comprising:
 1. an input shaft;
 2. a first planetary gearset having a ring gear, a pinion carrier, a planet pinion meshing withthe ring gear and rotatably journaled on the pinion carrier, and sungear meshing with the planet pinion, the ring gear being connected tosaid input shaft;
 3. a second planetary gear set having a ring gear, apinion carrier, a planet pinion meshing with the ring gear and rotatablyjournaled on the pinion carrier, and a sun gear meshing with the planetpinion, the ring gear being connected to the carrier of said firstplanetary gear set;
 4. a thiRd planetary gear set having a ring gear, apinion carrier, a planet pinion meshing with the ring gear and rotatablyjournaled on the pinion carrier, and a sun gear meshing with the planetpinion, the sun gear being connected with the sun gear of said secondplanetary gear set, the carrier being connected to said output shaft; 5.first clutch means for engaging said input shaft with the sun gear ofsaid first planetary gear set during operation of second and fourthforward speeds;
 6. second clutch means for engaging said input shaftwith the ring gear of said first planetary gear set, the carrier of saidsecond planetary gear set and the ring gear of said third planetary gearset during operation of third and fourth forward speeds;
 7. first brakemeans for anchoring the sun gear of said first planetary gear set duringoperation of first forward speed and reverse speed;
 8. second brakemeans for anchoring the pinion carrier of said second planetary gear setduring operation of reverse speed; and third brake means for anchoringthe sun gears of said second and said third planetary gear sets duringfirst, second and third forward speeds.
 2. a first planetary gear sethaving a ring gear, a pinion carrier, a planet pinion meshing with thering gear and rotatably journaled on the pinion carrier, and sun gearmeshing with the planet pinion, the ring gear being connected to saidinput shaft;
 2. A gear train according to claim 1, further comprisingone-way brake means for preventing the sun gear of said first planetarygear set from rotating in a direction opposite to the rotation directionof said input shaft.
 3. a second planetary gear set having a ring gear,a pinion carrier, a planet pinion meshing with the ring gear androtatably journaled on the pinion carrier, and a sun gear meshing withthe planet pinion, the ring gear being connected to the carrier of saidfirst planetary gear set;
 4. a thiRd planetary gear set having a ringgear, a pinion carrier, a planet pinion meshing with the ring gear androtatably journaled on the pinion carrier, and a sun gear meshing withthe planet pinion, the sun gear being connected with the sun gear ofsaid second planetary gear set, the carrier being connected to saidoutput shaft;
 5. first clutch means for engaging said input shaft withthe sun gear of said first planetary gear set during operation of secondand fourth forward speeds;
 6. second clutch means for engaging saidinput shaft with the ring gear of said first planetary gear set, thecarrier of said second planetary gear set and the ring gear of saidthird planetary gear set during operation of third and fourth forwardspeeds;
 7. first brake means for anchoring the sun gear of said firstplanetary gear set during operation of first forward speed and reversespeed;
 8. second brake means for anchoring the pinion carrier of saidsecond planetary gear set during operation of reverse speed; and thirdbrake means for anchoring the sun gears of said second and said thirdplanetary gear sets during first, second and third forward speeds.